A multiphoton laser scanning microscope is requested for the use of eight major users at the Mount Sinai School of Medicine. The instrument will be used for multichannel fluorescence and second harmonic generation imaging of a variety of organs and tissue preparations including both ex-vivo and in-vivo observations. The investigators, from the Departments of Gene and Cell Medicine, Immunobiology, Medicine, Neurology, Neurosurgery and Orthopedic Surgery, will study atherosclerotic plaques, HIV-associated nephropathy, tumor metastasis, tendon damage and repair, subarachnoid hemorrhage, vestibular sensory organs, immune system dynamics, and renal epithelial cell function. The instrument will be situated in and managed by the Microscopy Shared Resource Facility, an ongoing and successful institution-wide core which houses other confocal and widefield microscopes and is currently used by personnel from more than 100 Mount Sinai laboratories, The facility's staff of two full time biomedical engineers will provide supervision and training for users of the requested instrument and will be responsible for its maintenance.